| 1 | #!/usr/bin/env python2
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| 2 | """Test the with statement for Byterun."""
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| 3 |
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| 4 | from __future__ import print_function
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| 5 |
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| 6 | import unittest
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| 7 | import six
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| 8 |
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| 9 | import vmtest
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| 10 |
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| 11 | PY3 = six.PY3
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| 12 |
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| 13 | class TestWithStatement(vmtest.VmTestCase):
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| 14 |
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| 15 | def test_simple_context_manager(self):
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| 16 | self.assert_ok("""\
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| 17 | class NullContext(object):
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| 18 | def __enter__(self):
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| 19 | l.append('i')
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| 20 | # __enter__ usually returns self, but doesn't have to.
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| 21 | return 17
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| 22 |
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| 23 | def __exit__(self, exc_type, exc_val, exc_tb):
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| 24 | l.append('o')
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| 25 | return False
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| 26 |
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| 27 | l = []
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| 28 | for i in range(3):
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| 29 | with NullContext() as val:
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| 30 | assert val == 17
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| 31 | l.append('w')
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| 32 | l.append('e')
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| 33 | l.append('r')
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| 34 | s = ''.join(l)
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| 35 | print("Look: %r" % s)
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| 36 | assert s == "iwoeiwoeiwoer"
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| 37 | """)
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| 38 |
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| 39 | def test_raise_in_context_manager(self):
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| 40 | self.assert_ok("""\
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| 41 | class NullContext(object):
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| 42 | def __enter__(self):
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| 43 | l.append('i')
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| 44 | return self
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| 45 |
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| 46 | def __exit__(self, exc_type, exc_val, exc_tb):
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| 47 | assert exc_type is ValueError, \\
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| 48 | "Expected ValueError: %r" % exc_type
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| 49 | l.append('o')
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| 50 | return False
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| 51 |
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| 52 | l = []
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| 53 | try:
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| 54 | with NullContext():
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| 55 | l.append('w')
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| 56 | raise ValueError("Boo!")
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| 57 | l.append('e')
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| 58 | except ValueError:
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| 59 | l.append('x')
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| 60 | l.append('r')
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| 61 | s = ''.join(l)
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| 62 | print("Look: %r" % s)
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| 63 | assert s == "iwoxr"
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| 64 | """)
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| 65 |
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| 66 | def test_suppressed_raise_in_context_manager(self):
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| 67 | self.assert_ok("""\
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| 68 | class SuppressingContext(object):
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| 69 | def __enter__(self):
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| 70 | l.append('i')
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| 71 | return self
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| 72 |
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| 73 | def __exit__(self, exc_type, exc_val, exc_tb):
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| 74 | assert exc_type is ValueError, \\
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| 75 | "Expected ValueError: %r" % exc_type
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| 76 | l.append('o')
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| 77 | return True
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| 78 |
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| 79 | l = []
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| 80 | try:
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| 81 | with SuppressingContext():
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| 82 | l.append('w')
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| 83 | raise ValueError("Boo!")
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| 84 | l.append('e')
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| 85 | except ValueError:
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| 86 | l.append('x')
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| 87 | l.append('r')
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| 88 | s = ''.join(l)
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| 89 | print("Look: %r" % s)
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| 90 | assert s == "iwoer"
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| 91 | """)
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| 92 |
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| 93 | def test_return_in_with(self):
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| 94 | self.assert_ok("""\
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| 95 | class NullContext(object):
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| 96 | def __enter__(self):
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| 97 | l.append('i')
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| 98 | return self
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| 99 |
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| 100 | def __exit__(self, exc_type, exc_val, exc_tb):
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| 101 | l.append('o')
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| 102 | return False
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| 103 |
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| 104 | l = []
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| 105 | def use_with(val):
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| 106 | with NullContext():
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| 107 | l.append('w')
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| 108 | return val
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| 109 | l.append('e')
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| 110 |
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| 111 | assert use_with(23) == 23
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| 112 | l.append('r')
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| 113 | s = ''.join(l)
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| 114 | print("Look: %r" % s)
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| 115 | assert s == "iwor"
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| 116 | """)
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| 117 |
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| 118 | def test_continue_in_with(self):
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| 119 | self.assert_ok("""\
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| 120 | class NullContext(object):
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| 121 | def __enter__(self):
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| 122 | l.append('i')
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| 123 | return self
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| 124 |
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| 125 | def __exit__(self, exc_type, exc_val, exc_tb):
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| 126 | l.append('o')
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| 127 | return False
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| 128 |
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| 129 | l = []
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| 130 | for i in range(3):
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| 131 | with NullContext():
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| 132 | l.append('w')
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| 133 | if i % 2:
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| 134 | continue
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| 135 | l.append('z')
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| 136 | l.append('e')
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| 137 |
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| 138 | l.append('r')
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| 139 | s = ''.join(l)
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| 140 | print("Look: %r" % s)
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| 141 | assert s == "iwzoeiwoiwzoer"
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| 142 | """)
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| 143 |
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| 144 | def test_break_in_with(self):
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| 145 | self.assert_ok("""\
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| 146 | class NullContext(object):
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| 147 | def __enter__(self):
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| 148 | l.append('i')
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| 149 | return self
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| 150 |
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| 151 | def __exit__(self, exc_type, exc_val, exc_tb):
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| 152 | l.append('o')
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| 153 | return False
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| 154 |
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| 155 | l = []
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| 156 | for i in range(3):
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| 157 | with NullContext():
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| 158 | l.append('w')
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| 159 | if i % 2:
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| 160 | break
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| 161 | l.append('z')
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| 162 | l.append('e')
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| 163 |
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| 164 | l.append('r')
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| 165 | s = ''.join(l)
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| 166 | print("Look: %r" % s)
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| 167 | assert s == "iwzoeiwor"
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| 168 | """)
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| 169 |
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| 170 | def test_raise_in_with(self):
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| 171 | self.assert_ok("""\
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| 172 | class NullContext(object):
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| 173 | def __enter__(self):
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| 174 | l.append('i')
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| 175 | return self
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| 176 |
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| 177 | def __exit__(self, exc_type, exc_val, exc_tb):
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| 178 | l.append('o')
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| 179 | return False
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| 180 |
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| 181 | l = []
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| 182 | try:
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| 183 | with NullContext():
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| 184 | l.append('w')
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| 185 | raise ValueError("oops")
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| 186 | l.append('z')
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| 187 | l.append('e')
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| 188 | except ValueError as e:
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| 189 | assert str(e) == "oops"
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| 190 | l.append('x')
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| 191 | l.append('r')
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| 192 | s = ''.join(l)
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| 193 | print("Look: %r" % s)
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| 194 | assert s == "iwoxr", "What!?"
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| 195 | """)
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| 196 |
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| 197 | def test_at_context_manager_simplified(self):
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| 198 | self.assert_ok("""\
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| 199 | class GeneratorContextManager(object):
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| 200 | def __init__(self, gen):
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| 201 | self.gen = gen
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| 202 |
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| 203 | def __enter__(self):
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| 204 | try:
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| 205 | return next(self.gen)
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| 206 | except StopIteration:
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| 207 | raise RuntimeError("generator didn't yield")
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| 208 |
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| 209 | def __exit__(self, type, value, traceback):
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| 210 | if type is None:
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| 211 | try:
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| 212 | next(self.gen)
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| 213 | except StopIteration:
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| 214 | return
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| 215 | else:
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| 216 | raise RuntimeError("generator didn't stop")
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| 217 | else:
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| 218 | if value is None:
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| 219 | value = type()
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| 220 | try:
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| 221 | self.gen.throw(type, value, traceback)
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| 222 | raise RuntimeError(
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| 223 | "generator didn't stop after throw()"
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| 224 | )
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| 225 | except StopIteration as exc:
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| 226 | return exc is not value
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| 227 | except:
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| 228 | if sys.exc_info()[1] is not value:
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| 229 | raise
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| 230 |
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| 231 | def contextmanager(func):
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| 232 | def helper(*args, **kwds):
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| 233 | return GeneratorContextManager(func(*args, **kwds))
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| 234 | return helper
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| 235 |
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| 236 | @contextmanager
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| 237 | def my_context_manager(val):
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| 238 | yield val
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| 239 |
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| 240 | with my_context_manager(17) as x:
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| 241 | assert x == 17
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| 242 | """)
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| 243 |
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| 244 | def test_at_context_manager_complete(self):
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| 245 | # The complete code for an @contextmanager example, lifted from
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| 246 | # the stdlib.
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| 247 | self.assert_ok("""\
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| 248 | from _functools import partial
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| 249 |
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| 250 | WRAPPER_ASSIGNMENTS = ('__module__', '__name__', '__doc__')
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| 251 | WRAPPER_UPDATES = ('__dict__',)
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| 252 |
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| 253 | def update_wrapper(wrapper,
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| 254 | wrapped,
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| 255 | assigned = WRAPPER_ASSIGNMENTS,
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| 256 | updated = WRAPPER_UPDATES):
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| 257 | for attr in assigned:
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| 258 | setattr(wrapper, attr, getattr(wrapped, attr))
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| 259 | for attr in updated:
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| 260 | getattr(wrapper, attr).update(getattr(wrapped, attr, {}))
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| 261 | # Return the wrapper so this can be used as a decorator
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| 262 | # via partial().
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| 263 | return wrapper
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| 264 |
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| 265 | def wraps(wrapped,
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| 266 | assigned = WRAPPER_ASSIGNMENTS,
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| 267 | updated = WRAPPER_UPDATES):
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| 268 | return partial(update_wrapper, wrapped=wrapped,
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| 269 | assigned=assigned, updated=updated)
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| 270 |
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| 271 | class GeneratorContextManager(object):
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| 272 | def __init__(self, gen):
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| 273 | self.gen = gen
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| 274 |
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| 275 | def __enter__(self):
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| 276 | try:
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| 277 | return next(self.gen)
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| 278 | except StopIteration:
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| 279 | raise RuntimeError("generator didn't yield")
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| 280 |
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| 281 | def __exit__(self, type, value, traceback):
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| 282 | if type is None:
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| 283 | try:
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| 284 | next(self.gen)
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| 285 | except StopIteration:
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| 286 | return
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| 287 | else:
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| 288 | raise RuntimeError("generator didn't stop")
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| 289 | else:
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| 290 | if value is None:
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| 291 | value = type()
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| 292 | try:
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| 293 | self.gen.throw(type, value, traceback)
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| 294 | raise RuntimeError(
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| 295 | "generator didn't stop after throw()"
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| 296 | )
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| 297 | except StopIteration as exc:
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| 298 | return exc is not value
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| 299 | except:
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| 300 | if sys.exc_info()[1] is not value:
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| 301 | raise
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| 302 |
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| 303 | def contextmanager(func):
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| 304 | @wraps(func)
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| 305 | def helper(*args, **kwds):
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| 306 | return GeneratorContextManager(func(*args, **kwds))
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| 307 | return helper
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| 308 |
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| 309 | @contextmanager
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| 310 | def my_context_manager(val):
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| 311 | yield val
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| 312 |
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| 313 | with my_context_manager(17) as x:
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| 314 | assert x == 17
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| 315 | """)
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| 316 |
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| 317 | if PY3:
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| 318 | def test_generator_with_context_manager(self):
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| 319 | self.assert_ok("""\
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| 320 | from contextlib import contextmanager
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| 321 |
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| 322 | def inner():
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| 323 | yield "I'm inner!"
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| 324 |
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| 325 | def foo():
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| 326 | yield from inner()
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| 327 |
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| 328 | @contextmanager
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| 329 | def cmgr():
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| 330 | yield "Context Manager!"
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| 331 | raise StopIteration(cmgr())
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| 332 |
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| 333 | def main():
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| 334 | with (yield from foo()) as x:
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| 335 | print(x)
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| 336 |
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| 337 | def run(fn, *args):
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| 338 | x = fn(*args)
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| 339 | while True:
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| 340 | try:
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| 341 | print(next(x))
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| 342 | except StopIteration as e:
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| 343 | return e.value
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| 344 | run(main)
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| 345 | """)
|